A double-blind, placebo-controlled pilot study was conducted to evaluate the safety and efficacy of treatment of patients with Alzheimer's disease using monosialoganglioside GM-1, a neurotrophic factor. Of 46 patients enrolled, 42 completed all study requirements. Nineteen patients received 100 mg of GM-1 by daily intramuscular injection for 12 weeks. Twenty-three patients received placebo. Case evaluations were done at baseline, week 12, and week 24 and included both cognitive and psychosocial scales. Study results suggested that the treatment was safe, yet offered no overall symptomatic benefit to patients with mild-to-moderate Alzheimer's disease. Whether or not GM-1 therapy may offer protective benefit by slowing or arresting the progression of the disease remains unclear, since the results of the cognitive evaluations suggested that neither the GM-1 group nor the placebo group declined significantly during the 24-week study.